In modern rail vehicles, the increasing use of air suspension systems, which considerably improve ride quality, requires from a technical viewpoint the use of (anti-)roll stabilization systems in order to minimize roll oscillations, an (anti-)roll stabilization system basically consisting of a torsion bar spring, push/pull bars and two torsion bar bearing arrangements. The torsion bar spring generally runs transversely to the direction of travel, and is mounted on the car body. From both of its ends, the push/pull bars extend to the wheel truck. The roll stabilization system can also be disposed the other way round. In this case the torsion bar spring is mounted on the wheel truck. From both of its ends, the push/pull bars run to the car body. Each wheel truck can be provided with one or two torsion bar springs.
Particularly exacting requirements are placed on the bearing arrangement of the torsion bar spring, particularly in terms of freedom from play and low wear over a long period of use with Cardan deformability and high, well-defined stiffness. On the other hand, contamination of the sliding surfaces and sticking during the long period of service must be avoided with a high degree of reliability.
These requirements are particularly accentuated if one-piece torsion bar springs are used which are curved at the end. The bearing bushes and bearing shells of such torsion bar springs cannot be one-piece, as it would otherwise be impossible to slip them over the curved ends of the torsion bar spring or more precisely over the forged end pieces of the rods used for linkage to the push/pull bars. Rather the bearing bushes are of two-part or split design. The two-part design of the bearing shells (steel parts) exacerbates the problems of sealing the inside of the bearing to the outside and also of the required freedom from play, which means that the requirements in respect of minimal fouling, low wear and play as well as well-defined stiffness over a long period of use have yet to be satisfied.
For the reasons mentioned, when using anti-roll bar bearing arrangements on curved torsion bar springs according to the prior art, short bearing replacement intervals and/or an enhanced design with regreasing capability are required. For this purpose the bearing must be dismantled and the bearing bushes replaced, or grease must be applied to the bearing surface through a bore, e.g. via a grease nipple. With regard to distributing the grease over the entire sliding surface, it is additionally necessary to provide the bearing bush with grooves, which makes it more expensive to produce. Determining lubrication intervals increases maintenance work, noncompliance with the maintenance/lubrication intervals possibly detrimentally affecting the tribological pairing between torsion bar spring and bearing such that appreciable material abrasion may occur on the torsion bar spring—quite apart from an unacceptable level of bearing noise.
The use of split bearings can only be dispensed with if the torsion bar springs are implemented in a particular way whereby the levers in which the push/pull bars engage are connected to the torsion bar spring using a compression or keyed joint. The bearing arrangement is then located further out at the ends of the torsion bar spring. This design is not only expensive but also results in a very wide roll stabilization system.